In a wireless communication system of recent years, in order to improve a throughput between transmission and reception, there have been used techniques such as beam forming based on a plurality of antennas, space division multiplexing based on Multiple Input Multiple Output (MIMO), and the like. For example, when the beam forming is used, a transmitter is capable of increasing or decreasing an antenna gain for a specific direction, by controlling the phase and the amplitude of each antenna element.
Accordingly, it may be possible for the transmitter to form a transmission beam headed in a direction, in which a communication partner is located, and transmit a wireless signal, or form a null point (null steering) so as to reduce interference with another communication device different from the communication partner. In addition, as a technique for reducing the interference with the other communication device, for example, a technique has been known in which the size of a room is measured and on the basis of the measurement result, data communication is performed with a transmission output sufficient to cover the whole inside of the room and insufficient to reach an adjoining room. Japanese Laid-open Patent Publication No. 2003-174368 discusses such a technique.